As a high biologically toxic heavy metal ion, Cr(VI) will cause environmental pollution and endanger human health. Therefore, the development of fast, simple and visible detection methods for Cr(VI) is extremely important to control its harm. Toward this end, we report the establishment of a colorimetric sensing method for Cr(VI) based on single-atom nanozymes for enhanced detection performance. Firstly, we prepared SA-Fe/NG as peroxidase mimetic by anchoring Fe single-atom onto a single-layer of two-dimensional nitrogen-doped graphene. The SA-Fe/NG showed superiorly high oxidation catalytic activity due to its 100% atomic utilization and existing Fe-N-C structure. Furthermore, with 3,3′,5,5′-tetramethylbenzidine (TMB) as a colorimetric sensing probe, and 8-hydroxyquinoline (8-HQ) as an inhibitor for the oxidation of TMB, the detection of Cr(VI) was realized through specific interaction between Cr(VI) and 8-HQ, which led to the recovery of oxTMB in blue color. Our established method showed superior sensitivity with a detection limit of 3 nM and a linear range of 30 nM to 3 μM. It also exhibited high selectivity for a series of metal cations, and has been successfully applied to the detection of Cr(VI) in tap water and tuna samples.

Cr(VI)作为一种高生物毒性重金属离子，会造成环境污染，危害人类健康。因此，开发快速、简单、可见的 Cr(VI) 检测方法对于控制其危害极为重要。为此，我们报告了基于单原子纳米酶的 Cr(VI) 比色传感方法的建立，以提高检测性能。首先，我们通过将 Fe 单原子锚定在单层二维氮掺杂石墨烯上来制备 SA-Fe/NG 作为过氧化物酶模拟物。由于其 100% 的原子利用率和现有的 Fe-NC 结构，SA-Fe/NG 显示出极高的氧化催化活性。此外，以 3,3',5,5'-四甲基联苯胺 (TMB) 作为比色传感探针，8-羟基喹啉 (8-HQ) 作为 TMB 氧化的抑制剂，Cr(VI) 的检测是通过 Cr(VI) 与 8-HQ 之间的特定相互作用实现的，这导致 oxTMB 恢复为蓝色。我们建立的方法显示出卓越的灵敏度，检测限为 3 nM，线性范围为 30 nM 至 3 μM。它还对一系列金属阳离子表现出高选择性，并已成功应用于自来水和金枪鱼样品中 Cr(VI) 的检测。